Microscopy and microanalysis of complex nanosized strengthening precipitates in new generation commercial Al-Cu-Li alloys

作者：Guinel, M. J. -F.^*; Brodusch, N.; Sha, G.; Shandiz, M. A.; Demers, H.; Trudeau, M.; Ringer, S. P.; Gauvin, R.

来源：Journal of Microscopy, 2014, 255(3): 128-137.

DOI：10.1111/jmi.12143

• Atom probe tomography
• detection limit
• electron energy-loss spectroscopy (EELS)
• electron microscopy
• Monte Carlo simulations
• X-ray energy-dispersive spectrometry (XEDS)

Precipitates (ppts) in new generation aluminum-lithium alloys (AA2099 and AA2199) were characterised using scanning and transmission electron microscopy and atom probe tomography. Results obtained on the following ppts are reported: Guinier-Preston zones, T-1 (Al2CuLi), beta' (Al3Zr) and delta' (Al3Li). The focus was placed on their composition and the presence of minor elements. X-ray energy-dispersive spectrometry in the electron microscopes and mass spectrometry in the atom probe microscope showed that T-1 ppts were enriched in zinc (Zn) and magnesium up to about 1.9 and 3.5 at.%, respectively. A concentration of 2.5 at.% Zn in the delta' ppts was also measured. Unlike Li and copper, Zn in the T-1 ppts could not be detected using electron energy-loss spectroscopy in the transmission electron microscope because of its too low concentration and the small sizes of these ppts. Indeed, Monte Carlo simulations of EEL spectra for the Zn L-2,L-3 edge showed that the signal-to-noise ratio was not high enough and that the detection limit was at least 2.5 at.%, depending on the probe current. Also, the simulation of X-ray spectra confirmed that the detection limit was exceeded for the Zn K-alpha X-ray line because the signal-to-noise ratio was high enough in that case, which is in agreement with our observations.

• 出版日期2014-9
• 单位McGill